Certain sight flow products are known which allow visual inspection of fluid levels and/or flow. These sight flow products generally comprise a body which is cast in one-piece from, e.g., cast iron, steel or bronze. The body has an inlet and an outlet which are attached, e.g. threaded, bolted, soldered or welded, in-line with fluid pipes cooperatively forming a fluid flow line in a manufacturing plant or other facility. A transparent window mounted to the side of the body allows visual inspection of the fluid flow through the sight flow product, and hence the fluid flow within the fluid flow line. For example, a typical high pressure sight flow indicator is manufactured by the assignee of the present invention under the Model No. F-910-HP.
Some of these sight flow products have a fluid sensing device or indicator, e.g., a rotor, flapper, or condensation drip tube, mounted within the body. For example, the rotor or flapper can be rotatably mounted on an axle extending between and supported either by the windows on the body of the indicator, or by the body itself. The fluid sensing device facilitates visually inspecting the fluid flow within the indicator. For example, the rotor facilitates inspecting fluid flow within a sight flow indicator from a distance; while the flapper provides a positive indication of the direction of fluid flow. The condensation drip tube is particularly suited to be used with condensing or distillation fluid flows and similar apparatus having an intermittent flow.
The above-mentioned sight flow indicators, however, typically have the fluid sensing device mounted directly to the body or to the windows in the body. Accordingly, the entire body must be removed from its in-line connection if it becomes necessary or desirable to replace the sight flow indicator with an indicator having a different type of fluid sensing device.
Removing the entire sight flow indicator body from its in-line connection can interrupt the functioning of at least a portion of the plant or manufacturing facility. Further, if the sight flow indicator is to be entirely replaced, it is believed that surplus bodies must generally be kept on-hand, which can further increase storage and inventory costs.
Moreover, mounting the fluid sensing device directly to the body or to the windows necessarily limits the type of fluid sensing device used with a particular sight flow indicator. As indicated previously, the fluid sensing device or indicator cannot be interchanged between other sight flow indicator bodies. It is further believed that the detail, adjustment, variety, tolerances, etc., which can be manufactured into the indicator body are also limited by current technology and cost considerations. Consequently, the overall flexibility of the above-mentioned sight flow indicators can be limited.